Historically, both educational information and entertainment programs have been generated by content providers and delivered to users in a variety of formats, including printed publications, data storage media, and electronic broadcast signals. To access printed publications and data storage media, users are required to borrow or purchase the publications or media. This typically requires the users who desire access to travel to the information storage facilities to obtain the desired media, and in any case to store the media at the users' facilities for access at a time convenient for the users.
On the other hand, gaining access to information carried by broadcast signals is comparatively simpler, requiring only that the user tune a receiver in to the broadcast at the scheduled broadcast time. Unfortunately, the information sought by the user is available only at the time of broadcast, which may not necessarily be the time most convenient to the user.
Nevertheless, recognizing the advantages inherent in electronically broadcasting information, many content providers now electronically publish educational information for broadcast which was previously made available only in printed publications. A trend is therefore clearly emerging, colloquially termed the "information superhighway", in which large amounts of educational and entertainment programs and information ("multimedia") will be electronically available to a large number of users. Stated differently, multimedia encompasses both traditional audio-video television-type programs and programs spawned by the convergence of diverse industries and technologies including communications, computer, entertainment, publishing, film, and television, and multimedia programming is expected to be widely available.
Under certain circumstances, a user may be able to record a broadcast program for review at a later, more convenient time than the broadcast time. It will be appreciated, however, that requiring each user to store a particular program on a storage medium, e.g., a VCR, dedicated only to that user is inefficient. More particularly, each user must obtain his or her own storage medium and record the program separately from the storage media of other users, thereby duplicating resources and effort and consequently greatly increasing the overall cost to the users who wish to access the program.
Not surprisingly, attempts have been made to address the problem noted above by providing multimedia architectures which permit so-called "video-on-demand". Most of these architectures share the common attribute of requiring immense central data storage servers capable of storing vast amounts of data. These architectures necessarily entail unprecedented demands on the networks over which the data from the storage servers can be transmitted to users.
Unfortunately, a single motion picture requires several gigabytes of storage space. Accordingly, it will be appreciated that storing a full library of motion pictures, a full library of digitized literature and imagery, encyclopedic data, and so on, and, in turn, broadcasting such information on demand to various users at various times around the clock, would stretch and exceed the capacity of current storage and network technology.
In light of the above, it is an object of the present invention to provide a multimedia architecture for efficiently delivering video at user-defined times. Another object of the present invention is to provide a hierarchical multimedia delivery architecture which is easy to use and cost-effective.